For me, the best parts were the accessories and gadgets and chems, the vehicles and drones, and the customization rules. The weapons, and to some degree the armor, are mostly flavor and variety, though there are a few cool new items.

Spy gear, manatech, and drugs are very useful. A lot of detection gear, for example, or concealed equipment. The outdoor equipment is cool, but I haven't really come across a situation calling for it.
There's a better selection of vehicles than in the core book; finally something besides a Bulldog Step Van to ride around in. Things from the very small personal mobility vehicles, to RVs and up.
Similarly, there's a larger selection of drones to fill some additional roles, from minidrone killers to small blimps.
The customization rules are cool, and let you get a lot more functionality out of your vehicles and weapons.